The 1864 U.S. presidential election campaign—which was held the year after Robert E. Lee's defeat at Gettysburg—was an important one. As was the case in 1860, the North was divided. Judging by the dominant themes in campaign broadsides, this time the conflict was about the emancipation of the slaves, the prosecution of the Civil War, and the way to deal with the Confederate states. Abraham Lincoln was up for reelection, but doubted that he could win again, due to high casualties and military defeats. His opponent was the man whom he had removed as the general-in-chief during the war, George McClellan.

Lincoln was the candidate of the National Union Party, formed by pro-Lincoln Republicans and War Democrats, with the very effective slogan, "Don't change horses in the middle of a stream." McClellan positioned himself as a moderate who could end the war, with Lincoln depicted as too "extreme," since the president was for emancipation of the slaves in the South. The Currier & Ives print on the right shows McClellan calling for the preservation of the Union, while grabbing both Lincoln (saying "No peace without Abolition!") and Confederate President Jefferson Davis, with frayed pants (saying "No peace without Separation!").

One huge problem for McClellan, however, was that he had to run against his party's platform, which called for a "cessation of hostilities, with a view of an ultimate convention of the States" to restore the Union. McClellan wanted to continue the war, but Lincoln's campaign focussed on the danger of the Confederate States of America becoming an independent country, if the Democrats won.

Many states allowed Union soldiers to vote, and it was estimated that Lincoln won almost 80% of that segment. Three new states (West Virginia, Nevada, and Kansas) voted for the first time, and Lincoln won all three. Although McClellan won 45% of the popular vote, he was crushed in the Electoral College, winning only Kentucky, Delaware, and New Jersey. He almost won New York though—losing by less than 7,000 votes—when many immigrants were naturalized before the election and with fraud occurring in New York City. More than 70,000 soldiers from the state cast absentee ballots, which put Lincoln over the top.

McClellan’s cause was somewhat damaged by his party’s platform and his battlefield record, but his defeat has been attributed mainly to the Union capture of Atlanta two months before the election. The importance of the election of 1864 was obvious to Lincoln—he believed that the Democratic Party platform would lead to a McClellan administration negotiating an armistice, followed by the permanent breakup of the United States of America. Instead, Lincoln won reelection on a platform demanding that an amendment to the Constitution to abolish slavery be passed, and that the war would be pursued until the South was defeated and the Union preserved.